The present invention relates generally to chucks for use with drills or with electric or pneumatic power drivers. More particularly, the present invention relates to a chuck of the keyless type which may be tightened or loosened by hand or actuation of the driver motor.
Both hand and electric or pneumatic tool drivers are well known. Although twist drills are the most common tools on such drivers, the tools may also comprise screw drivers, nut drivers, burrs, mounted grinding stones, and other cutting or abrading tools. Since the tool shanks may be of varying diameter or of polygonal cross section, the device is usually provided with a chuck adjustable over a relatively wide range. The chuck may be attached to the driver by a threaded or tapered bore.
A variety of chucks have been developed in the art. In an oblique jawed chuck, a chuck body includes three passageways disposed approximately 120xc2x0 apart from each other. The passageways are configured so that their center lines meet at a point along the chuck axis forward of the chuck. The passageways constrain three jaws which are moveable in the passageways to grip a cylindrical or polygonal tool shank displaced approximately along the chuck center axis. The chuck includes a nut that rotates about the chuck center and that engages threads on the jaws so that rotation of the nut moves the jaws in either direction within the passageways. The body is attached onto the drive shaft of a driver and is configured so that rotation of the body in one direction with respect to the nut forces the jaws into gripping relationship with the tool shank, while rotation in the opposite direction releases the gripping relationship. The chuck may be keyless if it is rotated by hand. Examples of such chucks are disclosed in U.S. Pat. Nos. 5,125,673 and 5,193,824, commonly assigned to the present assignee and the entire disclosures of which are incorporated by reference herein. Various configurations of keyless chucks are known in the art and are desirable for a variety of applications.
The present invention recognizes and addresses the foregoing considerations, and others, of prior art constructions and methods.
Accordingly, it is an object of the present invention to provide an improved chuck.
This and other objects are achieved by a chuck for use with a manual or powered driver having a rotatable drive shaft. The chuck includes a generally cylindrical body having a nose section and a tail section. The tail section is configured to rotate with the drive shaft, and the nose section has an axial bore formed therein. A plurality of jaws are movably disposed with respect to the body in communication with the axial bore. A generally cylindrical sleeve is rotatably mounted about the body in operative communication with the jaws so that rotation of the sleeve in a closing direction moves the jaws toward the axis of the axial bore and rotation of the sleeve in an opening direction moves the jaws away from the axis. A bearing has a first race adjacent the body, a second race adjacent the sleeve and at least one bearing element disposed between the first race and the second race. One of the first race and the second race defines a ratchet. The other of the first race and the second race defines a pawl biased toward the ratchet. The ratchet and the pawl are configured so that when the pawl engages the ratchet, the ratchet and the pawl prevent the second race from rotating in the opening direction with respect to the first race.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one embodiment of the invention and, together with the description, serve to explain the principles of the invention.